/// <summary>
/// Decodes the operations at the specific address.
/// </summary>
/// <param name="address">The address.</param>
/// <returns></returns>
private IEnumerable <Operation> DecodeOperations(ushort address)
{
_halt = _stop = false;
_timer.Reset();
_index = _indexRegisterOperands[IndexRegister.HL];
_prefetch.ReBuildCache(address);
while (true)
{
// Reset
_operand1 = Operand.None;
_operand2 = Operand.None;
_flagTest = FlagTest.None;
_opCodeMeta = OpCodeMeta.None;
_decodeMeta = DecodeMeta.None;
_byteLiteral = 0x00;
_wordLiteral = 0x0000;
_displacement = 0x00;
var opCode = DecodeNextOpCode();
if (!opCode.HasValue)
{
continue;
}
if (_decodeMeta.HasFlag(DecodeMeta.Displacement))
{
_displacement = _prefetch.NextByte();
}
if (_decodeMeta.HasFlag(DecodeMeta.ByteLiteral))
{
_byteLiteral = _prefetch.NextByte();
}
if (_decodeMeta.HasFlag(DecodeMeta.WordLiteral))
{
_wordLiteral = _prefetch.NextWord();
}
yield return(new Operation(address,
opCode.Value,
_operand1,
_operand2,
_flagTest,
_opCodeMeta,
_byteLiteral,
_wordLiteral,
(sbyte)_displacement));
if (_decodeMeta.HasFlag(DecodeMeta.EndBlock))
{
yield break;
}
_index = _indexRegisterOperands[IndexRegister.HL];
address = unchecked ((ushort)(_prefetch.BaseAddress + _prefetch.TotalBytesRead));
}
}
private IInstructionTimingsBuilder UpdateDisplacement()
{
if (!_index.IsDisplaced)
{
return(_timer.Index(false));
}
_decodeMeta |= DecodeMeta.Displacement;
return(_timer.Index(true));
}
